我认为这实际上是非常直观的,但我无法弄清楚.
因此,我有一个名为SWS_Document的模型.然后,我有SWS_Document_Step,它具有SWS_Document的外键.接下来,我有第三个模型SWES_Step,它具有SWS_Document_Step的外键.本质上,SWES_Document_Step是SWS_Document_Step的子步骤.
例.将是“将黄油混入配方中”将是SWS_Document_Step.而SWES_Document_Step__id = 1将是“将黄油放入微波炉安全的碗中”. SWES_Document_Step__id = 2将是“微波黄油30秒”.
这些是将黄油混合到配方中的子步骤.
class SWS_Document(models.Model):
machines = models.ManyToManyField(Machine,related_name='SWS_documents')
document_description = models.CharField(max_length=150,default="")
pub_date = models.DateTimeField(auto_now=True)
class SWS_Document_Step(models.Model):
STEP_TYPE_CHOICES = (
('People','People'),('Quality','Quality'),('Velocity','Velocity'),('Cost','Cost'),)
document_number = models.ForeignKey(SWS_Document,on_delete=models.CASCADE)
sws_sequence_number = models.PositiveIntegerField(editable=True,null=True)
class SWES_Step(models.Model):
STEP_TYPE_CHOICES = (
('People',)
sws_document_id = models.ForeignKey(SWS_Document_Step,on_delete=models.CASCADE,null=True)
swes_description = models.CharField(max_length=500)
swes_step_type = models.CharField(max_length=8,choices=STEP_TYPE_CHOICES,blank=True)
pub_date = models.DateTimeField(auto_now=True)
因此,在我的view.py中,我采取了所有措施.
def DocumentView(request,document_id):
# final goal should be to pass a list full of lists...
# e.g. [
#[name1,[hazard1,hazard2],[assessment1,assessment2]],#[name2,[hazard3,hazard4],[assessment3,assessment4]],#]
steps = []
swsallsteps = SWS_Document_Step.objects.filter(document_number=document_id)
swesallsteps = SWES_Step.objects.filter(sws_document_id=document_id)
return render(request,'StandardWorkDocuments/document.html',{
'swsallsteps': swsallsteps,'swesallsteps': swesallsteps,})
然后在Document.html中,有一些for循环.
{% for step in swsallsteps %}
<button class='collapsible'>{{ step.sws_sequence_number }} - {{ step.sws_work_element_description}} - <em><b>{{step.sws_step_type}}</b></em> - published - {{step.pub_date}}</button>
<div class="content">
{% for swessteps in swesallsteps %}
<p>{{swessteps.swes_description}}</p>
{% endfor %}
</div>
{% endfor %}
本质上,我相信我要获取的是查询中的queryset.这样就可以了[[将黄油混入食谱中,[将黄油放入微波炉安全的碗中,将黄油微波30秒]]
This is what I’m currently getting
This is what I’d hope to get,with a few dumby points put in to show for example
最佳答案
您可以(并且应该)通过父项访问嵌套项. Django文档中有一些关于访问相关对象的有用的examples,在question中,您可以找到有关访问相关对象的更详细的清单.例如,related_name属性可以替换model_set语法并提高可读性(如果选择适当的话).
您的第二个循环应如下所示：
{% for swes_step in step.swes_step_set.all %}
<p>{{swes_step.swes_description}}</p>
{% endfor %}
现在,您不是从单独的查询集中而是从父步骤访问第二步骤级别.您可以抓取第二个查询集(swesallsteps).
为了避免发出大量的数据库查询,您应该使用prefetch_related以尽可能少的步骤获取所有数据：
swsallsteps = (SWS_Document_Step.objects
.filter(document_number=document_id)
.prefetch_related('swes_step_set')
)